Mouth closure means for bags comprising heat sealable material



Sept. 26, 1961 D. R. BURTON 3,001,689

MOUTH CLOSURE MEANS FOR BAGS COMPRISING HEAT SEALABLE MATERIAL Filed Oct. 24, 1958 lZa 1N VENTOR.

DRU/PY R BURTON A TTORNEYS United States Patent 0,

Chemical Company, Midland, Mich., a corporation of Delaware Filed Oct. 24, 1958, Ser. No. 769,447 3 Claims. (Cl. 229-62) This invention relates to packages and particularly to bags comprising heat scalable materials which bags are provided with easy-opening means.

Although the invention is not limited in its broader aspects to bags of any certain heat scalable material, it presently appears to be particularly advantageous with respect to stretchable films such as polyethylene because of their widespread use in packaging and the difiiculty or impossibility of accomplishing controlled tearing of stretchable films by tear tapes or strings or other commercially practical flexible package opening means.

The present invention contemplates the provision of a fibrous web piece, the opposite sides of which are heat sealed to the overlaying web portions of the bag walls which form the mouth closure of the bag. These overlaying web portions are releasably held in their overlaying relationship by the fibrous web piece and the overlaying web portions may be stripped from each other to open the mouth closure of the bag by pulling them apart to split the fibrous web piece.

A particular and important feature of the invention is the provision of heat seals on the opposite faces of the fibrous Web piece, which heat seals are themselves located in at least partially overlaying relationship with respect to each other. This arrangement causes the fibrous web piece to be subjected to acute prizing and splitting forces when the web portions forming the mouth closure of the bag are pulled apart.

Another feature of the invention is the provision of a difference in the Width of the heat seals on the opposite faces of the fibrous web piece. This feature establishes a closer control of the splitting action of the fibrous web piece and therefore an improved consistency of opening action.

These and other objects and advantages of the invention will become more fully apparent from the following description of several specific examples of the invention.

In the accompanying drawings:

FIGURE 1 is an elevation of a bag which illustrates one concrete embodiment of the invention.

FIGURE 2 is a fragmentary cross-sectional view on an enlarged scale taken from the plane of line 22 in FIGURE 1.

FIGURE 3 is a view similar to FIGURE 2 but illustrating the opening of the mouth closure.

FIGURE 4 is a fragmentary cross-sectional view of the mouth of a bag embodying the invention, opening of the mouth closure having been only partially accomplished.

FIGURE 5 is a fragmentary cross-sectional view of the mouth of still another bag embodying the invention prior to opening of the mouth closure.

FIGURE 6 is a schematic view illustrating a method of making bags contemplated by the present invention and intended to demonstrate the great practicality of the invention from a production standpoint.

Illustrated in FIGURES 1 and 2 is a bag 10 of heat scalable material, such as polyethylene or the like. The particular bag comprises a front wall 11 and a back wall 12. The upper edge portions 11a and 12a of the walls 11 and 12 will be seen to comprise overlaying web portions of heat scalable material which define the mouth closure of the bag. These web portions 11a and 12a are 3,001,689 Patented Sept. 26, 1961 ice held in overlaying relationship by a fibrous web piece 13 which is located between the web portions 11a and 12a and which is heat scalable on its opposite faces to each of the web portions 11a and 12a as by the heat seals indicated respectively by the reference numerals 14 and 15. This is to be contrasted with closures of the type shown, for example, in US. Patent 2,369,716 where a paper web is attached to the opposite sides of the mouth closure of a bag, but not in such a way that opposite faces of any piece of the paper web are so attached.

The fibrous web piece 13 may comprise an open-fiber paper or thin cardboard or it may comprise any other fibrous Web material capable of being bonded-to a heat scalable material such as polyethylene. For example, in some applications it may be desirable to employ fibrous webs which may be more accurately characterized as scrim or unwoven fabric than as paper stock.

It is to be noted that in the structure shown in FIG- URES 1 and 2, the heat seals 14 and 15 on the opposite faces of the fibrous web piece 13 are themselves located in overlaying relationship with respect to each other. That is, the entire width of the heat seal 14 will be seen in FIGURE 2 to overlay the heat seal 15. According to one important feature of the invention, it is highly desirable that such an overlaying relationship obtain at least to the extent that a portion of the width of the oppositely disposed heat seals are in overlaying relationship, that is, a relationship such that there is no gap between the heat seals in the transverse direction. If there is such a gap, then to the extent of the gap the fibrous web piece 13 will tend to bridge from the web portion 11a to the web portion 12a when these web portions are pulled apart to open the bag. This greatly reduces the degree of acuteness of the prizing action exerted on the fibrous web piece 13. 7

When the bag illustrated in FIGURES 1 and 2 is opened by pulling apart the web portions 11a and 12a, the fibrous web piece 13 is split across the heat seal between at least one of the web portions. In the particular bag, a split occurs across the heat seal 14, as shown in FIGURE 3, and the mouth closure is thus allowed to be opened. Because the heat seal 14 at least partially overlays the heat seal 15 and is not transversely spaced therefrom, pulling apart of the webs 11a and 12a subjects the fibrous web piece to an acute prizing action to readily efiect the splitting of the fibrous web piece across at least one of the heat seals.

In FIGURE 4 there is illustrated a similar structure including overlaying web portions 21a and 22a similar to the web portions 11a and 12a. A fibrous web piece 23 is heat sealed on its opposite faces to each of the web portions 21a and 22a. In this case the heat seals are both of the same width, as illustrated, and pulling apart of the web portions 21:: and 22a causes the fibrous Web piece 23 to split across the width of both the web portions. This split may occur more or less centrally within the thickness of the web piece 23, as shown. Again, since the oppositely disposed heat seals overlay each other, pulling apart of the web portions 21a and 22a subjects the fibrous Web piece 23 to an acute prizing action to readily split open the mouth closure.

In FIGURE 5 there is shown a bag having a front wall 31 and a rear wall 32. In this structure, one lip of the bag extends beyond the other to form an overlap portion 32a which will be understood to be equivalent in pertinent respects to the web portions 12a and 22a. The upper edge portion or lip of the front wall 31 of the bag constitutes a Web portion 31a which will be understood to be equivalent to the web portions 11a and 21a. The web portions 31a and 32a constitute a pair of overlaying web portions which define the mouth closure and they are held in their overlaying relationship by a fibrous web piece 33 which is located between them and which is heat sealed on its opposite faces to each of them in the man ner illustrated.

In the case of tubular bags, already formed, fibrous web pieces equivalent to the web pieces 13, 23 and 3-3 may be prfe-coated on one or both sides with the heat sealable material which the bag walls are to comprise, or not precoated, and may be inserted in the mouth of the bags after the bags are filled. Alternatively, they may be ins'e'rted before filling and may be sealed on one side to one web portion which is to define month closure of the bag and may be thereafter sealed to the associated opposite web portion after filling of the bag.

A preferred method of fabricating bags embodying the invention is illustrated in' FIGURE 6. A webl of polyethylene or the like is provided having a tape 3 of the fibrous web material laminated to it. The web v1 is then folded to'enclos'e the strip 3 as indicated and the folded web is then cut transversely by a hot knife at the stage A to sever the .web into bag lengths while simultaneously welding the severed edges to produce a side welded bag 10. a

The above description of the invention should make it apparent thatmany details of the concrete examples of the invention may be varied without departing from the teaching of the invention. Accordingly, the scope of the invention is not to be limited to precise details of the specifically described embodiments but is to be defined by the following claims.

What is claimed is:

1. An article of manufacture including a bag comprising heat scalable material and having a mouth closure which is to be opened to allow materials contained in the bag to be removed from the bag, the mouth closure be ing defined by a pair of overlaying web portions of the heat scalable material, which web portions are held in overlaying relationship but which web portions are to be stripped away from each other to' open the mouth closure, 2. fibrous web piece between said web portions and heat sealed on its opposite faces to each of them to releasably hold them in said overlaying relationship, whereby pulling apart said web portions and thereby splitting the fibrous web piece across the heat seal between it and at least one of said web portions allows the mouth closure to be opened.

2. An article of manufacture including a bag comprising heat sealable material and having a mouth closure which is to be opened to allow materials contained in the bag to be removed from the bag, the mouth closure being defined by a pair of overlaying web portions of the heat sealable material, which web portionsare held in overlaying relationship but which web portions are to be stripped away from each other to open the mouth closure, 2 fibrous web piece between said Web portions and heat sealed on its opposite faces to each of them to releasably hold them in said overlaying relationship, the heat seals on the opposite faces of said fibrous web piece being themselves located in at least partially overlaying relationship withrespect to each other whereby pulling apart said web portions subjects said fibrous web piece to acute prizing and, splitting forces.

7 3. An article of manufacture including a bag comprising heat scalable material and having a mouth closure which is to be opened to allow materials contained in the bag to be removed from the bag, the mouth closure being defined by a pair of overlaying web portions of the heat sealable material, which Web portions are held in overlaying relationship but which web portions are to be stripped away from each other to open the mouth closure, a fibrous web piece between said web portions and heat sealed on its opposite faces to each of them to releasably hold them in said overlaying relationship, the heat seal on one face of said fibrous web piece being wider than the heat seal on the opposite face of said fibrous web piece, the heat seals on the opposite faces of said fibrous 'web piece being themselves located in at least partially overlaying relationship with respect to each other whereby pulling apart said web portions subjects said fibrous web piece to acute prizing and splitting forces.

References Cited in the file of this patent UNITED STATES PATENTS Howard Dec. 12, 1944 2,648,463 Scherer Aug. 11, 1953 2,819,010 Arniguet Ian. 7, 1958 FOREIGN PATENTS 552,804 Great Britain Apr. 27, 1943 

